Oil-based ink composition for ink-jet recording

ABSTRACT

An oil-based ink composition for ink jet recording of the present invention contains a colorant and at least 50% by weight of a mixed solvent made by mixing from 0.02 to 4 parts by weight of a lactone-type solvent with 1 part by weight of polyoxyethylene glycol dialkyl ether represented by the following general formula (1):  
     R 11 —(OC 2 H 4 ) n —OR 12   General Formula (1)  
     (wherein R 11 , R 12  represent alkyl groups having from 1 to 3 carbon atoms and can be the same or different, and n is an integer from 2 to 4). The oil-based ink composition can be suitably used for printing on a polyvinyl chloride substrate and is excellent in all of print quality, printing stability, dry characteristics of printed matter, and storage stability of ink.

FIELD OF THE INVENTION

[0001] The present invention relates to an oil-based ink composition forink jet recording.

BACKGROUND ART

[0002] As ink jet recording system, there are known various ink jetrecording systems such as a system (electric field controlling system)in which ink is discharged using electrostatic attraction, a system(drop-on-demand system or pressure pulse system) in which ink isdischarged using the oscillation pressure of a piezoelectric element,and a system (bubble or thermal system) in which ink is discharged usingpressure developed by forming bubbles and allowing them to grow withheat. By any one of these systems, highly detailed images can beobtained.

[0003] In these ink jet recording systems, aqueous ink using water as amain solvent, and oil-based ink using an organic solvent as a mainsolvent are generally used. Matters printed with aqueous ink aregenerally poor in water resistance and printing with the aqueous ink onrecording media having water-proof surface is difficult. On the otherhand, oil-based ink has advantages that it can provide printed matterswhich are excellent in water resistance and that it can facilitate theprinting on recording media having water-proof surface or wood freepapers. Further, oil-based ink using pigment as colorant is excellent inlight stability.

[0004] In conventional oil-based ink, however, an aromatic hydrocarbonsuch as toluene or xylene, an aliphatic hydrocarbon such as hexane orkerosene, a ketone group such as methyl-ethyl ketone, an ester groupsuch as ethyl acetate, or propylene glycol mono-methyl ether acetate isgenerally used as organic solvent. However, the oil-based ink has thefollowing problems. When printing is conducted on a polyvinyl chloridesubstrate as a recording medium with such an ink using organic solventas mentioned above, nozzles are easily clogged because such an organicsolvent has low boiling point and low flash point so as to easily dry.In addition, it is expensive to satisfy the printer specificationbecause of the dissolving and swelling properties of such an organicsolvent relative to plastics (for example, polystyrene resin and ABSresin) used in ink storage containers, apparatuses such as a printer,and parts thereof. Further, when printing is conducted on a polyvinylchloride substrate, such oil-based ink cannot provide satisfactory printquality nor provide satisfactory dry characteristics of printed matter.

[0005] It is an object of the present invention to provide an oil-basedink composition for ink jet recording which can be suitably used forprinting on a polyvinyl chloride substrate and is excellent in all ofprint quality, printing stability, dry characteristics of printedmatter, and storage stability of ink.

DISCLOSURE OF THE INVENTION

[0006] An oil-based ink composition for ink jet recording of the presentinvention is characterized in that the oil-based ink compositioncontains a colorant and at least 50% by weight of a mixed solvent madeby mixing from 0.02 to 4 parts by weight of a lactone-type solvent with1 part by weight of polyoxyethylene glycol dialkyl ether represented bythe following general formula (1):

R¹¹—(OC₂H₄)_(n)—OR¹²  General Formula (1)

[0007] (wherein R¹¹, R¹² represent alkyl groups having from 1 to 3carbon atoms and can be the same or different, and n is an integer from2 to 4).

[0008] The oil-based ink composition is characterized in that thelactone-type solvent is a γ-lactone-type solvent.

[0009] The oil-based ink composition is characterized in that theγ-lactone-type solvent is γ-butyrolactone or γ-valerolactone.

[0010] The oil-based ink composition further contains from 0.01% to 48%by weight of at least one selected from solvents includingpolyoxyethylene glycol monoalkyl ether represented by the followinggeneral formula (2.), polyoxypropylene glycol monoalkyl etherrepresented by the following general formula (3), and triethyl citrate.

R²¹—(OC₂H₄)_(n)—OH  General Formula (2)

[0011] (wherein R²¹ represents alkyl groups having from 1 to 6 carbonatoms and n is an integer from 3 to 6)

R³¹—(OC₃H₆)_(n)—OH  General Formula (3)

[0012] (wherein R³¹ represents alkyl groups having from 1 to 4 carbonatoms and n is an integer from 2 to 3).

[0013] The oil-based ink composition is characterized in that theoil-based ink composition further contains a binder resin.

[0014] The oil-based ink composition is characterized in that the binderresin is (meth)acrylic resin.

[0015] The oil-based ink composition is characterized in that the (meth)acrylic resin is a homopolymer of methyl methacrylate or a copolymer ofmethyl methacrylate and butyl methacrylate.

[0016] The oil-based ink composition is characterized in that the (meth)acrylic resin has a molecular weight of from 10,000 to 150,000 and has aglass-transition temperature (Tg) of 40° C. or more.

[0017] The oil-based ink composition is characterized in that the(meth)acrylic resin and vinyl chloride-vinyl acetate copolymer resinand/or cellulose-type resin are used together as the binder resin.

[0018] The oil-based ink composition is used for printing on a polyvinylchloride substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] An oil-based ink composition for ink jet recording (hereinafter,sometimes referred to as only “oil-based ink composition”) of thepresent invention comprises colorant and solvent. The solvent containsat least 50% by weight of a mixed solvent made by mixing from 0.02 to 4parts by weight of a lactone-type solvent with 1 part by weight ofpolyoxyethylene glycol dialkyl ether represented by the above mentionedgeneral formula (1) and preferably further contains from 0.01% to 48% byweight of at least one selected from solvents including polyoxyethyleneglycol monoalkyl ether represented by the abovementioned general formula(2), polyoxypropylene glycol monoalkyl ether represented by theabovementioned general formula (3), and triethyl citrate. The colorantand binder resin are suitably dissolved or dispersed in the solvent witha dispersant, thereby obtaining the oil-based ink composition.

[0020] The present invention is based on the finding that lactone-typesolvents are excellent in permeability relative to a polyvinyl chloridesubstrate and that the lactone-type solvents can provide ink havingexcellent leveling property and drying property when used together withpolyoxyethylene glycol dialkyl ether represented by the abovementionedgeneral formula (1). In addition, the lactone-type solvent and thepolyoxyethylene glycol dialkyl ether represented by the abovementionedgeneral formula (1) have high boiling points and low vapor pressure sothat they provide good working environment.

[0021] The mixed solvent (hereinafter, referred to as “mixed solvent”)obtained by mixing the polyoxyethylene glycol dialkyl ether representedby the abovementioned general formula (1) (hereinafter, referred to as“polyoxyethylene glycol dialkyl ether”) and the lactone-type solventwill be described.

[0022] The polyoxyethylene glycol dialkyl ether is represented by theabovementioned general formula (1) wherein R¹¹, R¹² are straight-chainor branched-chain alkyl groups and has a boiling point of 150° C. ormore, preferably 180° C. or more at an atmospheric pressure. Thoughthere is no particular limitation of the upper limit, the upper limitmay be about 240° C. considering the function thereof as an ink for inkjet recording. In addition, the density of the polyoxyethylene glycoldialkyl ether at a temperature of 20° C. is 0.9 g/cm³ or more.

[0023] Specific examples of polyoxyethylene glycol dialkyl ethers arediethylene glycol dimethyl ether, triethylene glycol dimethyl ether,tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether,triethylene glycol diethyl ether, tetraethylene glycol diethyl ether,diethylene glycol ethyl methyl ether, triethylene glycol ethyl methylether, tetraethylene glycol ethyl methyl ether, diethyleneglycol-di-n-propyl ether, and diethylene glycol-di-iso-propyl ether.Among them, diethylene glycol diethyl ether, triethylene glycol dimethylether, and diethylene glycol ethyl methyl ether are preferable.

[0024] The lactone-type solvent is a compound having ring structureformed by ester bonds such as γ-lactone having a 5-membered ringstructure, δ-lactone having a 6-membered ring structure, or ε-lactonehaving a 7-membered ring structure. Specific examples areγ-butyrolactone, γ-valerolactone, γ-hexalactone, γ-heptalactone,γ-octalactone, γ-nonalactone, γ-decalactone, γ-undecalactone,δ-valerolactone, δ-hexalactone, δ-heptalactone, δ-octalactone,δ-nonalactone, δ-decalactone, δ-undecalactone, and ε-caprolactone.

[0025] In the preferred embodiment of the present invention, thelactone-type solvent is γ-lactone having a 5-membered ring structure,more preferably, γ-butyrolactone, or γ-valerolactone.

[0026] In the mixed solvent, the lactone-type solvent is preferably from0.02 to 4 parts by weight, more preferably from 0.05 to 2 parts byweight, relative to 1 part by weight of the polyoxyethylene glycoldialkyl ether represented by the abovementioned general formula (1). Theoil-based ink composition preferably contains at least 50% by weight,more preferably 70% by weight or more, of the mixed solvent, whereby theoil-based ink composition becomes excellent in permeability relative toa polyvinyl chloride substrate, leveling property, and drying property.

[0027] In the oil-based ink composition for ink jet recording of thepresent invention, at least one selected from solvents represented bythe abovementioned general formulae (2), (3) and triethyl citrate ispreferably used in addition to the mixed solvent in order to prevent thevolatilization and solidification of the oil-based ink composition atnozzles or inside tubes and to resolve the oil-based ink compositionwhen solidified.

[0028] In the polyoxyethylene glycol monoalkyl ether represented by theabovementioned general formula (2), R²¹ is an alkyl group having from 1to 6, preferably from 1 to 4 carbon atoms and n is an integer from 3 to6. Specific examples are triethylene glycol monomethyl ether,triethylene glycol monobutyl ether, tetraethylene glycol monomethylether, tetraethylene glycol monobutyl ether, pentaethylene glycolmonomethyl ether, hexaethylene glycolmonomethyl ether. These may be usedalone or in mixed state. The polyoxyethylene glycol monoalkyl ether hasa boiling point of from 200° C. to 305° C., preferably 240° C. to 305°C. at an atmospheric pressure.

[0029] For the same purpose of the compound represented by theaforementioned general formula (2), nonionic polyoxyethylene derivativewhich is liquid at a room temperature and atmospheric pressure may beadded. Specific examples include polyoxyethylene cetyl ethers such asNissan Nonion P-208 (available from NOF Corporation) as polyoxyethylenealkyl ether series, polyoxyethylene oleyl ethers such as Nissan NonionE-202S, E-205S (available from NOF Corporation), polyoxyethylene laurylethers such as EMALGEN 106, 108 (available from Kao Corporation),polyoxyethylene octyl phenol ethers such as Nissan Nonion HS-204,HS-205, HS-206, HS-208 (available from NOF Corporation) aspolyoxyethylene alkyl phenol ether series, sorbitan monocaprylate suchas Nissan Nonion CR-08R (available from NOF Corporation) as sorbitanmonoester series, sorbitan monolaurate such as Nissan Nonion LP-20R(available from NOF Corporation), polyoxyethylene sorbitan monostearatesuch as Nissan Nonion OT-221 (available from NOF Corporation) aspolyoxyethylene sorbitan monoester series, polymeric surfactant ofpolycarboxylic acid series such as FLOWLEN G-70 (available from KyoeishaChemical Co., Ltd.), polyoxyethylene higher alcohol ethers such asEMALGEN 707, 709 (available from Kao Corporation), tetraglycerin oleatesuch as POEM J-4581 (available from Riken Vitamin Co., Ltd.), nonylphenol ethoxylate such as ADEKA TOL NP-620, NP-650, NP-660, NP-675,NP-683, NP686 (available from Asahi Denka Co., Ltd.), aliphaticphosphate esters such as ADEKA COL CS-141E, TS230E (available from AsahiDenka Co., Ltd.), sorbitan sesquioleate such as SORGEN 30 (availablefrom Dai-ich Kogyo Seiyaku Co., Ltd.), sorbitan monooleate such asSORGEN 40 (available from Dai-ich Kogyo Seiyaku Co., Ltd.), polyethyleneglycol sorbitan monolaurate such as SORGEN TW-20 (available from Dai-ichKogyo Seiyaku Co., Ltd.), polyethylene glycol sorbitan monooleate suchas SORGEN TW-80 (available from Dai-ich Kogyo Seiyaku Co., Ltd.).Besides the above examples, surface active agents of acetylene glycolseries represented by the following formula may be employed:

[0030] (wherein 0≦p+q≦50, and R⁴¹, R⁴², R⁴³, R⁴⁴ are alkyl groups,preferably alkyl groups having from 1 to 6 carbon atoms).

[0031] Specific examples are 2,4,7,9-tetramethyl-5-decyne-4,7-diol,3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-l-hexyne-3-ol. Examplesas commercial products include Surfynol 104, 82, 465, 485, or TG (all ofthem are available from Air Products and Chemicals, Inc.) Olfine STG,Olfine E1010 (available from Nissin Chemical Industry Co., Ltd.), NissanNonion A-10R, A-13R (available from NOF Corporation), FLOWLEN TG-740W,D-90 (available from Kyoeisha Chemical Co., Ltd.), EMALGEN A-90, A-60(available from Kao Corporation), and NOIGEN CX-100 (available fromDai-ich Kogyo Seiyaku Co., Ltd.). These polyoxyethylene derivatives maybe added alone or in the mixed state.

[0032] Examples as polypropylene glycol monoalkyl ether represented bythe general formula (3) include dipropylene glycol monomethyl ether,dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether,dipropylene glycol monobutyl ether, and tripropylene monomethyl ether.These may be used alone or in the mixed state. The polypropylene glycolmonoalkyl ether has a boiling point of from 170° C. to 245° C.,preferably from 180° C. to 240° C. at an atmospheric pressure.

[0033] The solvents represented by the abovementioned general formulae(2), (3) and triethyl citrate can impart the effect of inhibitingvolatilization to the oil-based ink composition, thereby preventing theink composition from evaporating in the tube for supplying the ink froman ink cartridge to a printer head so as to prevent or reduce thedeposition of solid content of the ink composition. The content rate ofthe solvent is from 0.01 to 48% by weight, preferably from 5 to 30% byweight of the oil-based ink composition.

[0034] Though the solvents represented by the abovementioned generalformulae (2), (3) and triethyl citrate may be used alone, variousproperties such as the dispersion stability of the colorant, theevaporation of the ink, and the viscosity of the ink can be controlledby adding two or more of them in combination.

[0035] Now, components to be dispersed or dissolved in theaforementioned solvent in the ink composition for ink jet recording ofthe present invention will be described.

[0036] Inorganic or organic pigments and dyes, which are generally usedin conventional ink compositions, may be used as the colorant. Examplesas the pigments include carbon black, cadmium red, molybdenum red,chrome yellow, cadmium yellow, titanium yellow, chrome oxide, viridian,titanium cobalt green, ultra marine blue, Persian blue, cobalt blue,diketo pyrrolo pyrrole, anthraquinone, benzimidazolone,anthrapyrimidine, azo-based pigments, phthalocyanine-based pigments,quinacridone-based pigments, iso-indolinone-based pigments,dioxazine-based pigments, threne-based pigments, perylene-basedpigments, perynone-based pigments, tioindigo-based pigments,quinophthalone-based pigments, and metal chelate pigments. Examples asthe dyes include azo dyes, metal chelate dyes, naphtol dyes,anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes,xanthene dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes,benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes, and metalphthalocyanine dyes. Among these, the oil soluble dyes are particularlypreferable. These pigments and dyes may be used alone or in combinationsthereof as necessary. Pigments are better in terms of weatherresistance. The volume-mean particle diameter of primary particles ofthe pigment is from 50 to 500 nm, preferably from 50 to 200 nm.

[0037] The content rate of the colorant is from 0.5% to 25% by weight,preferably from 0.5% to 15% by weight, more preferably from 1% to 10% byweight in the oil-based ink composition.

[0038] Any dispersant which is usually used in oil-based inkcompositions, particularly in oil-based ink composition for ink jetrecording can be used as the dispersant. Preferable dispersant is adispersant effectively acting when the solubility parameter of theorganic solvent is from 8 to 11. Commercial products having suchcharacteristics may be used as the dispersant. Specific examples of suchcommercial products are polymers of polyester-type such as HinoactoKF1-M, T-6000, T-7000, T-8000, T-8350P, T-8000EL (available from TakefuFine Chemicals Co., Ltd.), solsperse 20000, 24000, 32000, 32500, 33500,34000, 35200 (available from Avecia K.K.), disperbyk-161, 162, 163, 164,166, 180, 190, 191, 192 (available from BYK-Chemie GmbH), FLOWLENDOPA-17, 22, 33, G-700 (available from Kyoeisha Chemical Co., Ltd.),AJISPER PB821, PB711 (available from Ajinomoto-Fine-Techno Co., Inc.),LP4010, LP4050, LP4055, POLYMER 400, 401, 402, 403, 450, 451, 453(available from EFKA chemicals B.V.). These may be used alone or in themixed state.

[0039] The content ratio of the dispersant in the oil-based inkcomposition of the present invention is from 5% to 200% by weight,preferably from 30% to 120% by weight, relative to the content of thecolorant (particularly pigment) in the ink composition. The content rateof the dispersant can be suitably selected according to the pigment tobe dispersed.

[0040] The oil-based ink composition for ink jet recording of thepresent invention preferably contains a binder resin. The binder resinhas solubility relative to the solvent and is added for the purpose ofcontrolling the degree of viscosity of the oil-based ink composition andfor providing the fixability relative to the polyvinyl chloridesubstrate. Examples are acrylic resin, stylene acrylic resin, modifiedrosin resin, phenol resin, terpene resin, polyester resin, polyamideresin, epoxy resin, vinyl chloride-vinyl acetate copolymer resin,cellulose-type resin such as cellulose acetate butyrate, and vinyltoluene-α-methylstylene copolymer resin. These can be used alone or inthe mixed state.

[0041] The binder resin is preferably (meth) acrylic resin, that is,acrylic resin or methacrylic resin, more preferably a homopolymer ofmethyl methacrylate or a copolymer of methyl methacrylate and butylmethacrylate.

[0042] The molecular weight of the (meth) acrylic resin is from 10,000to 150,000, preferably from 10,000 to 100,000. The glass-transitiontemperature (Tg) of the (meth)acrylic resin is 40° C. or more. Thoughthere is no particular limitation of the upper limit, the upper limit ofthe glass-temperature is preferably 105° C.

[0043] Vinyl chloride-vinyl acetate copolymer resin and/orcellulose-type resin such as cellulose acetate butyrate are preferablyused together with the (meth)acrylic resin, thereby increasing theadhesion relative to the substrate and controlling the viscosity of theink.

[0044] The content rate of the binder resin is from 0.5 to 3 times,preferably from 0.75 to 1.6 times as the adding amount of the colorant(by weight).

[0045] Stabilizers such as an antioxidant and ultraviolet ray absorbentand/or surface-active agent can be added to the oil-based inkcomposition of the present invention. Examples of antioxidants includesBHA (2,3-butyl-4-oxyanisole), BHT (2,6-di-t-butyl-p-cresol). The contentratio of the antioxidant is from 0.01% to 3.0% by weight in theoil-based ink composition. As the ultraviolet ray absorbent, abenzophenone compound or a benzotriazole compound may be employed. Thecontent ratio of the ultraviolet ray absorbent is from 0.01% to 0.5% byweight in the oil-based ink composition. As the surface-active agent,any of cationic, anionic, amphoteric, and nonionic surface active agentsmay be used. The content ratio of the surface-active agent is from 0.5%to 4.0% by weight in the oil-based ink composition.

[0046] According to the preparing method of the oil-based inkcomposition for ink jet recording of the present invention, the mixedsolvent or a mixture made by mixing the solvent selected from a groupconsisting of the solvent represented by the abovementioned generalformulae (2), (3) and triethyl citrate with the mixed solvent isemployed as the solvent as the oil-based ink composition. The pigmentand the dispersant are added to a part of the aforementioned solvent andmixed and dispersed by a ball mill, a bead mill, an ultrasonichomogenizer, or a jet mill so as to prepare a pigment dispersed liquid.The balance of the abovementioned solvent, the binder resin, and otheradditives are added to the obtained pigment dispersed liquid withconducting agitation.

[0047] The oil-based ink composition for ink jet recording thus obtainedis adjusted to have a viscosity of from 2 to 10 mPa·s, preferably from 3to 5 mPa·s at a temperature of 20° C.

[0048] The surface tension of the oil-based ink composition of thepresent invention is preferably from 20 to 50 mN/m. The surface tensionless than 20 mN/m makes the ink composition to spread over the surfaceof the printer head for the ink jet recording or to leak out of theprinter head so that the suitable ink drop discharge becomes difficult.The surface tension exceeding 50 mN/m disturbs proper spread of the inkover the surface of the recording medium, thus making the properprinting impossible.

[0049] The oil-based ink composition of the present invention has anadvantage that it is inert to the surface of the discharge nozzleprocessed by ink repellent treatment. Therefore, the oil-based inkcomposition of the present invention can be advantageously used in anink jet recording system in which ink is discharged from a printer headfor ink jet recording having a discharge nozzle processed by the inkrepellent treatment.

[0050] The oil-based ink composition for ink jet recording of thepresent invention is suitably adopted to the recording on a plasticsubstrate as a recording medium, particularly the recording on a rigidor flexible polyvinyl chloride substrate. Examples of polyvinyl chloridesubstrates include films and sheets. The oil-based ink composition forink jet recording of the present invention has a beneficial effect ofenabling the printing on a polyvinyl chloride substrate having surfaceswithout treatment, thereby eliminating the use of expensive recordingmedia such as conventional recording media having receiving layers. Ofcourse, the oil-based ink composition of the present invention can beadopted to the recording on a recording media of which surface istreated with ink receivable resin.

[0051] Hereinafter, the present invention will be described withconcrete examples. However, these examples do not limit the scope of thepresent invention.

[0052] The viscosity was measured by using a viscometer “AMVn” availablefrom Anton Paar GmbH. The particle diameter of pigment particles wasmeasured by using “Microtrac UPA150” available from Nikkiso Co., Ltd.

EXAMPLE 1

[0053] A solvent of the following composition was prepared:Υ-butyrolactone 40.0 parts by weight diethylene glycol diethyl ether28.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight triethylene glycol monomethyl ether 11.0 parts by weiqht

[0054] 3.5 parts by weight of carbon black (“MA-8” available fromMitsubishi Chemical Corporation) and 2.0 parts by weight of a dispersant(a polymer compound of polyester-type “Hinoacto KF1-M” available fromTakefu Fine Chemicals Co., Ltd.) were added to a part of the solvent ofthe abovementioned composition and was agitated at 3,000 rpm by adissolver for 1 hour. After that, the mixture was preliminarilydispersed by a bead mill filled with zirconia beads (2 mm). The meanparticle diameter of pigment particles thus obtained was 5 μm or less.

[0055] Further, the preliminarily dispersed mixture was mainly dispersedby a nano mill filled with zirconia beads (0.3 mm) so as to obtainpigment-dispersed liquid. The mean particle diameter of pigmentparticles obtained by this main dispersion was 60 nm.

[0056] With agitating the obtained pigment-dispersed liquid at 4,000rpm, 3.0 parts by weight of a binder resin (a copolymer of methylmethacrylate and butyl methacrylate “Paraloid B-99N”, available fromRohm and Haas Company, having a molecular weight of 15,000 and aglass-transition temperature of 82° C.) and the balance of the mixedsolvent prepared in the above were added, thereby preparing an oil-basedink composition for ink jet recording of the present invention. Theviscosity was 4.1 mPa·s (at 20° C.).

EXAMPLE 2

[0057] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight triethylene glycol monomethyl ether 11.0 parts by weight

[0058] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.0 mPs·s (at 20° C.).

EXAMPLE 3

[0059] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight tetraethylene glycol monobutyl ether 11.0 parts by weight

[0060] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.2 mPs·s (at 20° C.).

EXAMPLE 4

[0061] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether52.0 parts by weight dipropylene glycol monomethyl ether 12.0 parts byweight triethyl citrate 11.0 parts by weight

[0062] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.2 mPa·s (at 20° C.).

EXAMPLE 5

[0063] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight triethylene glycol diethyl ether50.0 parts by weight dipropylene glycol monomethyl ether 11.0 parts byweight tetraethylene glycol monobutyl ether 11.0 parts by weight

[0064] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.1 mPa·s (at 20° C.).

COMPARATIVE EXAMPLE 1

[0065] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether 5.0 parts by weight dipropylene glycol monomethyl ether 55.0 parts byweight triethylene glycol monomethyl ether 12.0 parts by weight

[0066] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.4 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 2

[0067] A solvent of the following composition was prepared: diethyleneglycol diethyl ether 48.0 parts by weight dipropylene glycol monomethylether 33.0 parts by weight tetraethylene glycol monobutyl ether 11.0parts by weight

[0068] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 3.9 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 3

[0069] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight tripropylene glycol dimethyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight tetraethylene glycol monobutyl ether 11.0 parts by weight

[0070] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.4 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 4

[0071] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol dibutyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight tetraethylene glycol monomethyl ether 11.0 parts by weight

[0072] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 1 except that the solvent of theabovementioned composition was used instead of the solvent of Example 1.The viscosity was 4.0.mPs·s (at 20° C.).

[0073] Printing was conducted on a polyvinyl chloride film (Viewcal 900:available from Lintec Corporation) by an ink jet printer (MJ-8000C;available from Seiko Epson Corporation) loaded with each of the inksprepared in Example 1 through Example 5, Comparative Example 1 throughComparative Example 4.

[0074] Matters printed with inks of Example 1 through Example 6,Comparative Example 1 through Comparative Example 4 were evaluated asfollows and the results are shown in Table 1.

[0075] (1) Print Quality

[0076] Solid image and thin line pattern were printed. At that time,printed matters were visually observed to evaluate reproducibility. Theresults are shown in a row of Evaluation 1 in Table 1.

[0077] A: No blur was observed.

[0078] B: Ink Slightly blurred, but the printed pattern remains.

[0079] C: Ink blurred widely so as to spoil the formation of images.

[0080] (2) Printing Stability

[0081] The continuous printing was conducted at a room temperature. Atthat time, inspection was performed for dropouts of dots, curving motionof flying droplets, and satellite ink droplets.

[0082] A: The number of occurrences of dropouts of dots, curving motionof flying droplets, or satellite ink droplets after the elapse of 48hours from the start of the printing was less than 10.

[0083] B: The number of occurrences of dropouts of dots, curving motionof flying droplets, or satellite ink droplets after the elapse of 48hours from the start of the printing was from 10 to less than 20.

[0084] C: The number of occurrences of dropouts of dots, curving motionof flying droplets, or satellite ink droplets after the elapse of 24hours from the start of the printing was 20 or more.

[0085] (3) Dry Characteristics

[0086] Solid image was printed. Time until the image dried at atemperature of 30° C. was measured.

[0087] A: Within 5 minutes.

[0088] B: From 5 minutes to 10 minutes.

[0089] C: 10 minutes or longer.

[0090] (4) Storage Stability of Ink

[0091] 50g of each ink composition was put in a glass bottle and theglass bottle was then hermetically sealed. The ink composition was leftin this state at 60° C. for one week. After that, the ink compositionwas measured for properties, that is, the viscosity and the particlesize distribution.

[0092] A: The difference in measurements of viscosity and particle sizedistribution between before being left and after being left was lessthan 5%.

[0093] B: The difference in measurements of viscosity and particle sizedistribution between before being left and after being left was lessthan 10%.

[0094] C: The difference in measurements of viscosity and particle sizedistribution between before being left and after being left was 10% ormore. TABLE 1 Evaluation Comparative Comparative Comparative ComparativeItems Example 1 Example 2 Example 3 Example 4 Example 5 Example 1Example 2 Example 3 Example 4 1 A A A A A C C C B 2 A A A A A A A B C 3A A A A A C C C A 4 A A A A A B A B C

[0095] It was found from the above table that the oil-based inkcompositions for ink jet recording of the present invention weresatisfactory on all of the evaluation items. Comparative Examples 1 and2 were poor in print quality and dry characteristics and ComparativeExample 1 had some trouble in the storage stability of ink. ComparativeExample 3 was poor in print quality and dry characteristics and had sometrouble in the printing stability and the storage stability of ink.Comparative Example 4 was poor in printing stability and storagestability of ink and had some trouble in the print quality.

EXAMPLE 6

[0096] A solvent of the following composition was prepared:Υ-valerolactone 52.0 parts by weight diethylene glycol diethyl ether30.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0097] 3.0 parts by weight of carbon black (C.I. PIGMENT BLACK 7) and2.0 parts by weight of a dispersant (a polymer compound ofpolyester-type “solsperse 32000” available from Avecia K.K.) were addedto a part of the solvent of the abovementioned composition and wasagitated at 3,000 rpm by a dissolver for 1 hour. After that, the mixturewas preliminarily dispersed by a bead mill filled with zirconia beads (2mm). The mean particle diameter of pigment particles thus obtained was 5μm or less.

[0098] Further, the preliminarily dispersed mixture was mainly dispersedby a nano mill filled with zirconia beads (0.3 mm) so as to obtainpigment-dispersed liquid. The mean particle diameter of pigmentparticles obtained by this main dispersion was 60 nm.

[0099] With agitating the obtained pigment-dispersed liquid at 4,000rpm, 3.0 parts by weight of a binder resin (“Paraloid B-99N”, availablefrom Rohm and Haas Company) and the balance of the mixed solventprepared in the above were added, thereby preparing an oil-based inkcomposition for ink jet recording of the present invention. Theviscosity was 3.9 mPa·s (at 20° C.).

EXAMPLE 7

[0100] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0101] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 3.9 mPa·s (at 20° C.).

EXAMPLE 8

[0102] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether50.0 parts by weight dipropylene glycol monomethyl ether 12.0 parts byweight tetraethylene glycol monobutyl ether 10.0 parts by weight

[0103] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.2 mPa·s (at 20° C.).

EXAMPLE 9

[0104] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether50.0 parts by weight dipropylene glycol monomethyl ether 12.0 parts byweight triethyl citrate 10.0 parts by weight

[0105] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.2 mPa·s (at 20° C.).

EXAMPLE 10

[0106] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weiqht triethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0107] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.0 mPs·s (at 20° C.).

EXAMPLE 11

[0108] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0109] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.2 mPa·s (at 20° C.).

EXAMPLE 12

[0110] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight triethylene glycol diethyl ether62.5 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0111] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that “Paraloid B-60” available from Rohm and Haas Company (copolymerof methyl methacrylate and butyl methacrylate having a molecular weightof 60,000 and a glass-transition temperature of 75° C.) was used insteadof the binder resin of Example 6 and its adding amount was 2.5 parts byweight. The viscosity was 4.1 mPa·s (at 20° C.).

EXAMPLE 13

[0112] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether63.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0113] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that “DEGALAN M825” available from Degussa Roehm GmbH (polymethylmethacrylate having a molecular weight of 80,000 and a glass-transitiontemperature of 105° C.) was used instead of the binder resin of Example6 and its adding amount was 2.0 parts by weight. The viscosity was 4.4mPs·s (at 20° C.).

EXAMPLE 14

[0114] A solvent of the following composition was prepared:Υ-hexalactone 20.0 parts by weight diethylene glycol diethyl ether 62.0parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0115] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.2 mPs·s (at 20° C.).

EXAMPLE 15

[0116] A solvent of the following composition was prepared:δ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0117] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.2 mPs·s (at 20° C.).

EXAMPLE 16

[0118] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.5 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0119] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that “Paraloid B-67” available from Rohm and Haas Company(poly(isobutyl methacrylate) having a molecular weight of 60,000 and aglass-transition temperature of 50° C.) was used instead of the binderresin of Example 6 and its adding amount was 2.5 parts by weight. Theviscosity was 4.1 mPs·s (at 20° C.).

EXAMPLE 17

[0120] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0121] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that 2.4 parts by weight of “Paraloid B-60” available from Rohm andHaas Company (copolymer of methyl methacrylate and butyl methacrylatehaving a molecular weight of 60,000 and a glass-transition temperatureof 75° C.) and 0.6 parts by weight of “UCAR Solution vinyl VROH”available from Nihon Union Carbide Corporation (vinyl chloride-vinylacetate copolymer having a molecular weight of 15,000 and aglass-transition temperature of 65° C.) were used instead of the binderresin of Example 6. The viscosity was 4.3 mPs·s (at 20° C.).

EXAMPLE 18

[0122] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0123] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that 2.9 parts by weight of “Paraloid B-60” available from Rohm andHaas Company (copolymer of methyl methacrylate and butyl methacrylatehaving a molecular weight of 60,000 and a glass-transition temperatureof 75° C.) and 0.1 parts by weight of “CAB381-0.1” available fromEastman Chemical (cellulose-type resin having a molecular weight of20,000 and a glass-transition temperature of 123° C.) were used insteadof the binder resin of Example 6. The viscosity was 4.3 mPs·s (at 20°C.).

EXAMPLE 19

[0124] A solvent of the following composition was prepared:Υ-valerolactone 20.0 parts by weight diethylene glycol diethyl ether62.7 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0125] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6and that 2.3 parts by weight of “Paraloid B-66” available from Rohm andHaas Company (copolymer of methyl methacrylate and butyl methacrylatehaving a molecular weight of 7,000 and a glass-transition temperature of50° C.) was used instead of the binder resin of Example 6. The viscositywas 4.3 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 5

[0126] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether 5.0 parts by weight dipropylene glycol monomethyl ether 55.0 parts byweight triethylene glycol monomethyl ether 12.0 parts by weight

[0127] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.4 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 6

[0128] A solvent of the following composition was prepared: diethyleneglycol diethyl ether 48.0 parts by weight dipropylene glycol monomethylether 33.0 parts by weight tetraethylene glycol monobutyl ether 11.0parts by weight

[0129] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 3.9 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 7

[0130] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight tripropylene glycol dimethyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight tetraethylene glycol monobutyl ether 11.0 parts by weight

[0131] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.4 mPs·s (at 20° C.).

COMPARATIVE EXAMPLE 8

[0132] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol dibutyl ether48.0 parts by weight dipropylene glycol monomethyl ether 13.0 parts byweight triethylene glycol monomethyl ether 11.0 parts by weight

[0133] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 6 except that the solvent of theabovementioned composition was used instead of the solvent of Example 6.The viscosity was 4.0 mPs·s (at 20° C.).

EXAMPLE 20

[0134] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether62.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0135] 3.0parts by weight of C.I. PIGMENT BLUE (15:3) as colorant and2.0 parts by weight of a dispersant (a polymer compound ofpolyester-type “solsperse 32000” available from Avecia K.K.) were addedto a part of the solvent of the abovementioned composition and wasagitated at 3,000 rpm by a dissolver for 1 hour. After that, the mixturewas preliminarily dispersed by a bead mill filled with zirconia beads (2mm). The pigment particles thus obtained were 5 μm or less.

[0136] Further, the preliminarily dispersed mixture was mainly dispersedby a nano mill filled with zirconia beads (0.3 mm) so as to obtainpigment-dispersed liquid. The mean particle diameter of pigmentparticles obtained by this main dispersal was 130 nm.

[0137] With agitating the obtained pigment-dispersed liquid at 4,000rpm, 3.0 parts by weight of a binder resin (“Paraloid B-99N”, availablefrom Rohm and Haas Company) and the balance of the mixed solventprepared in the above were added, thereby preparing an oil-based inkcomposition for ink jet recording of the present invention. Theviscosity was 3.9 mPa·s (at 20° C.).

EXAMPLE 21

[0138] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether60.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0139] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 20 except that the solvent of theabovementioned composition was used instead of the solvent of Example20, that 3.0 parts by weight of C.I. PIGMENT RED 122 was used instead ofthe colorant of Example 20, and that 4.0 parts by weight of a dispersant(a polymer compound of polyester-type “solsperse 33500” available fromAvecia K.K.) was used instead of the dispersant of Example 20. Theviscosity was 4.2 mPs·s (at 20° C.).

EXAMPLE 22

[0140] A solvent of the following composition was prepared:Υ-butyrolactone 20.0 parts by weight diethylene glycol diethyl ether60.0 parts by weight tetraethylene glycol monobutyl ether 10.0 parts byweight

[0141] An oil-based ink composition for ink jet recording was preparedin the same manner as in Example 20 except that the solvent of theabovementioned composition was used instead of the solvent of Example20, that 3.0 parts by weight of C.I. PIGMENT YELLOW 150 was used insteadof the colorant of Example 20, and that 4.0 parts by weight of adispersant (a polymer compound of polyester-type “solsperse 33500”available from Avecia K.K.) was used instead of the dispersant ofExample 20. The viscosity was 4.3 mPs·s (at 20° C.).

[0142] Printing was conducted on a polyvinyl chloride film (Viewcal 900:available from Lintec Corporation) by an ink jet printer (MJ-8000C;available from Seiko Epson Corporation) loaded with each of the inksprepared in Example 6 through Example 22, Comparative Example 5 throughComparative Example 8.

[0143] Matters printed with inks of Example 6 through Example 22,Comparative Example 5 through Comparative Example 8 were evaluated inthe same manner as the above and the results are shown in Table 2 andTable 3. TABLE 2 Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Evaluationample ample ample ample ample ample ample ample ample ample ample Items6 7 8 9 10 11 12 13 14 15 16 1 A A A A A A A A A A B 2 A A A A A A A A AA A 3 A A A A A A A A B B A 4 A A A A A A A A B B A

[0144] TABLE 3 Ex- Ex- Ex- Ex- Ex- Ex- Evaluation ample ample ampleample ample ample Comparative Comparative Comparative Comparative Items17 18 19 20 21 22 Example 5 Example 6 Example 7 Example 8 1 A A A A A AC C C B 2 A A A A A A A A B C 3 A A A A A A C C C A 4 A A A A A A B A BC

[0145] It was found from the above tables that the oil-based inkcompositions for ink jet recording of the present invention weresatisfactory on all of the evaluation items. Comparative Examples 5 and6 were poor in print quality and dry characteristics and ComparativeExample 5 had some trouble in the storage stability of ink. ComparativeExample 7 were poor in print quality and dry characteristics and hadsome trouble in the printing stability and the storage stability of ink.Comparative Example 8 had poor printing stability and storage stabilityof ink and had some trouble in the print quality.

INDUSTRIAL APPLICABILITY

[0146] The oil-based ink composition for ink jet recording of thepresent invention can be suitably used for printing on a polyvinylchloride substrate and is excellent in all of print quality, printingstability, dry characteristics of printed matter, and storage stabilityof ink.

1. An oil-based ink composition for ink jet recording, wherein the oil-based ink composition contains a colorant and at least 50% by weight of a mixed solvent made by mixing from 0.02 to 4 parts by weight of a lactone-type solvent with 1 part by weight of polyoxyethylene glycol dialkyl ether represented by the following general formula (1): R¹¹—(OC₂H₄)_(n)—OR¹²  General Formula (1) (wherein R¹¹, R¹² represent alkyl groups having from 1 to 3 carbon atoms and can be the same or different, and n is an integer from 2 to 4).
 2. An oil-based ink composition for ink jet recording as claimed in claim 1, wherein the lactone-type solvent is γ-lactone-type solvent.
 3. An oil-based ink composition for ink jet recording as claimed in claim 2, wherein the γ-lactone-type solvent is γ-butyrolactone or γ-valerolactone.
 4. An oil-based ink composition for ink jet recording as claimed in claim 1, wherein the oil-based ink composition further contains from 0.01% to 48% by weight of at least one selected from solvents including polyoxyethylene glycol monoalkyl ether represented by the following general formula (2), polyoxypropylene glycol monoalkyl ether represented by the following general formula (3), and triethyl citrate: R²¹ (OC₂H₄)_(n)—OH  General Formula (2) (wherein R²¹ represents alkyl groups having from 1 to 6 carbon atoms and n is an integer from 3 to 6) R³¹—(OC₃H₆)_(n)—OH  General Formula (3) (wherein R³¹ represents alkyl groups having from 1 to 4 carbon atoms and n is an integer from 2 to 3).
 5. An oil-based ink composition for ink jet recording as claimed in claim 1, wherein the colorant is a pigment.
 6. An oil-based ink composition for ink jet recording as claimed in claim 1, wherein the oil-based ink composition further contains a binder resin.
 7. An oil-based ink composition for ink jet recording as claimed in claim 6, wherein the binder resin is (meth) acrylic resin.
 8. An oil-based ink composition for ink jet recording as claimed in claim 7, wherein the (meth)acrylic resin is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and butyl methacrylate.
 9. An oil-based ink composition for ink jet recording as claimed in claim 7, wherein the (meth)acrylic resin has a molecular weight of from 10,000 to 150,000 and has a glass-transition temperature (Tg) of 40° C. or more.
 10. An oil-based ink composition for ink jet recording as claimed in claim 6, wherein the (meth)acrylic resin and vinyl chloride-vinyl acetate copolymer resin and/or cellulose-type resin are used together as the binder resin.
 11. An oil-based ink composition for ink jet recording as claimed in claim 1, wherein the oil-based ink composition is used for printing on a polyvinyl chloride substrate. 